Group A meningococcal carriage in travelers returning from Saudi Arabia.

In August 1987, an outbreak of group A meningococcal meningitis occurred during the annual pilgrimage to Mecca, Saudi Arabia, resulting in an attack rate among American pilgrims of 640 per 100,000. To determine risk factors for carriage, throat cultures were taken from passengers arriving on four consecutive flights from Saudi Arabia to the United States. Pilgrims were more likely to be group A meningococcal carriers than were nonpilgrims (relative risk, 11.1; 95% confidence interval, 3.7 to 33.1). Smoking, crowding, and meningococcal vaccination were not significantly associated with group A carriage. Pilgrims complaining of recent fever or sore throat, however, were more likely to be group A carriers, consistent with previous reports linking carriage and disease to preceding viral infections. Serogrouping of invasive meningococcal isolates can be used to monitor for indigenous transmission of this unusual strain in the United States, and we recommend routine vaccination of pilgrims to prevent future outbreaks of meningococcal disease.